My reason for disrecommending the S7 is exactly that. Even in ideal mining condition, such as 0.05$/kWh ~ and 2-4% diff increase from now on, no more 5% and such, no pool fee and no BTC price plummeting, the S7 will not ROI by halving, at which point any profit after that is dubious at best.
We do not know what will happen at halving. Prices could go up or yes many miners will have to stop. We cannot say with any certainty this far away.
One thing to keep in mind is the selling of the machines. Even if someone has higher electricity they can mine with it for quiet a while. S7 will still hold value at around having, they might have to sell to ROI. But with owning a newer miner the good thing is value is better. Look at SP20, S4 S5, Avalon 4.1 to show the trend of miner still having good value even though they are not the most current.
I agree, which is why i don't think the S7 will maintain its price. This may sound counter intuitive but here is why;
When the S5 first came out, the price per GH was 0.3$~ After all this time, the S5's are still reasonably worth something. But is that because units don't devalue that much or because the S5 was properly priced from the start? S5's are about 0.2$~/GH now.
Now look at the S7, already went down... 100$? And the Price per GH is over 0.4$ door to door. About double a S5, and half electricity consumption does not mean double the value.
I would value the S7 at 0.3$/GHs, no more. Each GH return much less last year, when S5's were introduced, yet the price per GH on the S7 is much higher.
Why? Because Bitmain has monopoly.